The present invention relates generally to an electrical connector system for use with an implantable medical device such as a pacemaker for connecting an implantable electrical lead to the electrical circuits contained within a hermetically sealed housing of the medical device.
While the present invention will be described in a specific manner as being applicable to a pacemaker, it will be understood that the invention is applicable to any other type of implantable medical device intended to stimulate body tissue.
Modem pacemakers monitor the activity of a heart and provide a stimulation pulse in the absence of normal heart activity. Advantageously, such devices are relatively small, light-weight and implantable. In order to sense and stimulate the heart, however, such pacemakers must be used with a pacemaker lead, an electrical conductor that carries electrical signals between the heart and the pacemaker. Advantageously, the pacemaker lead can be inserted into the heart transvenously through a relatively simple and well-known surgical procedure. Disadvantageously, one end of the lead (designated herein as the xe2x80x9cconnecting endxe2x80x9d) must be electrically and mechanically secured to the pacemaker in a way that provides for a long-term safe and secure, yet detachable connection. Those skilled in the pacemaker art have long sought for a simple, yet reliable and safe, technique for making this detachable electrical and mechanical connection between the pacemaker device and the connecting end of the pacemaker lead.
In order to appreciate the advantages of the present invention, it will help first to have a basic understanding of the manner in which the mechanical and electrical connection functions are carried out in known pacemakers. The main components associated with the connection function of such known pacemakers are shown diagrammatically in FIG. 1. A pacemaker 10 electrically includes a battery 14 that powers electrical circuits 12. The pacemaker electrical circuits 12 and battery 14 are mechanically enclosed and hermetically sealed in a suitable housing 16. Typically, this housing or case 16 is shaped to include a flat side or platform 20 to which a suitable epoxy connector 22 can be bonded. At least one feedthrough terminal, 18, in electrical contact with the electrical circuits 12, passes through the case or housing 16 and protrudes beyond the platform 20. This feedthrough terminal 18 is electrically isolated from the case 16. A platinum wire 24, or other suitable conductive element, connects the terminal 18 to a conductive connector block 26 that is fitted within the connector 22. A pacemaker lead 28, having a proximal electrode 30, connects to the pacemaker electrical circuits by inserting the proximal electrode 30 into a receiving channel 31 of the connector 22 until the electrode 30 is in contact with the connector block 26. A set screw 32 is then securely tightened using a torque wrench 34 to firmly hold the electrode 30 in both mechanical and electrical connection with the connector block 26. A septum, not shown but having the construction generally described in commonly assigned U.S. Pat. No. 5,509,928 issued Apr. 23, 1996 to Acken, is typically placed over the set screw 32 in order to prevent body fluids from seeping through the set screw hole. Further, sealing ribs or ridges 36 on the connecting end of the pacemaker lead are designed to tightly engage the inside edges of the receiving channel 31 in order to prevent any body fluids from entering into the receiving channel 31 once the connecting end of the lead has been inserted into the connector 22.
While the descriptions presented in the prior art vary greatly relative to, for example, different types of locking mechanisms for performing the mechanical connection function, or different types of arrangements for performing the electrical feedthrough function, including the use of bipolar or multiple pacemaker leads, all such systems include the use of a premolded or cast connector 22 that is bonded to a sealed pacemaker housing 16 in which the electrical circuits are located.
Typically, prior art connectors 22 are cast in place from epoxy to the platform or header 20 of the pacemaker, or a premolded connector is bonded to the platform 20 using a suitable sealing and bonding agent. Further, once the electrical connection is made from the terminal post 18 to the connector block 26, and the connector is attached to the housing, all remaining voids within the connector 22, not including the receiving channel 31 into which the proximal end of the pacemaker lead 28 is to be inserted, must be filled with a suitable filler material, such as a two-component epoxy or silicone rubber.
As is evident from the above description, placing a connector on a pacemaker housing is a very labor-intensive process involving many components. What is needed is a similar manner of lead attachment that provides the requisite mechanical and electrical connection functions using fewer components and less labor yet providing higher reliability. The present invention addresses these and other needs.
In a subsequent development, as disclosed in U.S. Pat. No. 5,951,595 issued Sep. 14, 1999 to Moberg et al., an active lock but passive release connector assembly includes an entrance block leading to lead receiving channels of an implantable medical device provided with two seals which, when compressed by the entrance block, lock onto the body of each lead. As one drawback of the Moberg et al. device, it periodically occurs that when the leads need to be extracted and the mechanism is released, causing the plunger to move back away from the seals, it sometimes occurs that the seals remain tightly locked onto the leads after the plunger is released from the seals. This requires a higher extraction force than should normally be necessary. In the present invention, in contrast, when the mechanism is loosened, the clamp is actively released from the lead body, enabling the lead to then be easily extracted from the device.
It was with knowledge of the foregoing state of the technology that the present invention has been conceived and is now reduced to practice.
A connector system for use with a sealed implantable medical device includes an entrance block attached to the medical device with an inlet bore for receiving an electrical lead such that, when attached to the medical device, the inlet bore is coaxial with the lead receiving channel of the medical device. A clamp assembly within the entrance block includes a mounting member, a cylindrically shaped loop clamp unitary with the mounting member having an adjustable diameter, the loop clamp being coaxial with the inlet bore and movable between a first position disengaged from the electrical lead and freely permitting withdrawal of the electrical lead from the inlet bore and a second position firmly engaged with the electrical lead received in the inlet bore so as to prevent its withdrawal from the inlet bore, and an actuator mechanism for shifting the loop clamp between the first and second positions.
In a preferred design the connector system is intended for use with an implantable medical device having a pair of lead receiving channels while incorporating all of the features of the single lead receiving channel design.
It is a feature of the present invention to provide an electrical connector system for use with an implantable medical device such as a pacemaker for connecting an implantable electrical lead to the electrical circuits contained within a hermetically sealed housing of the medical device.
It is a further feature of the present invention to provide such an electrical connector system which enables the electrical leads to be readily selectively firmly attached to the medical device in one instance and just as readily detached in another instance.
Still a further feature of the present invention is to provide such an electrical connector which includes an entrance block attached to the medical device and having an inlet bore for reception therethrough of the electrical lead and, when positioned for attachment to the medical device, the inlet bore being coaxial with the lead receiving channel, a clamp assembly within the entrance block including a mounting member, a cylindrically shaped loop clamp unitary with the mounting member having an adjustable diameter, the loop clamp being coaxial with the inlet bore and movable between a first position disengaged from the electrical lead and freely permitting withdrawal of the electrical lead from the inlet bore and a second position firmly engaged with the electrical lead received in the inlet bore so as to prevent its withdrawal from the inlet bore, and an actuator mechanism for shifting the loop clamp between the first and second positions.
Yet a further feature of the present invention is to provide such an electrode assembly with a construction which activates with a special driver stylet
A still further feature of the present invention is to provide such an electrical connector in which the entrance block includes first and second opposed spaced apart side walls, with a first retainer bore in the first side wall extending transverse of the inlet bore and a second retainer bore in the second side wall generally aligned with the first retainer bore, in which the actuator mechanism includes an actuator block with a threaded bore therein aligned with the first and second retainer bores, an actuating screw having a head rotatably received in the first retainer bore, being threadedly engaged with the threaded bore of the actuator block, and extending to a terminal journal rotatably received in the second retainer bore and in which the loop clamp extends between a first end at the mounting member and a second end fixed to the actuator block, whereby rotation of the actuating screw in one direction shifts the loop clamp from the first position to the second position and whereby rotation of the actuating screw in the opposite direction shifts the loop clamp from the second position to the first position.
Yet another feature of the present invention is to provide such an electrical connector which includes an annular seal received in the inlet bore of the entrance block adjacent the clamp assembly, the annular seal being coaxial and aligned with the inlet bore for sealing engagement with the electrical lead when the electrical lead is received in the inlet bore.
Yet a further feature of the present invention is to provide such an electrical connector according to which the annular seal has an inner peripheral surface and at least one rim member projecting inwardly from the inner peripheral surface, the rim member being sealingly engaged with the electrical lead when the electrical lead is received in the inlet bore.
Other and further features, advantages, and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory but are not to be restrictive of the invention. The accompanying drawings which are incorporated in and constitute a part of this invention, illustrate one of the embodiments of the invention, and together with the description, serve to explain the principles of the invention in general terms. Like numerals refer to like parts throughout the disclosure.